Capacitor-discharge ignition systems are known for driving the ignition coil of an internal-combustion engine. Such capacitor-discharge ignition systems have included a constant frequency oscillator driving a single power FET which, in response to the oscillator, applies an input voltage across a single primary winding of a step-up transformer to charge a load capacitor for driving an ignition coil.
Although such capacitor-discharge ignition systems adequately drive an ignition coil, the use of a transformer having a single primary winding that receives an input voltage in response to the switching of a single power FET requires that the primary have a large number of turns for storing energy in the form of inductance which is utilized during the off-times of the power FET. To store a sufficient amount of energy in the transformer, an input current having a large peak amplitude must be provided through the primary of the transformer during the periods when the power FET is activated. The large peak input current in the primary tends to generate noise which necessitates the use of costly electrolytic filtering capacitors that will not succumb to the high ambient temperatures associated with internal combustion engines.